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auto_increment.go
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auto_increment.go
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// Copyright 2020-2021 Dolthub, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package expression
import (
"fmt"
"gopkg.in/src-d/go-errors.v1"
"github.com/Sndav/go-mysql-server/sql"
)
var (
// ErrAutoIncrementUnsupported is returned when table does not support AUTO_INCREMENT.
ErrAutoIncrementUnsupported = errors.NewKind("table %s does not support AUTO_INCREMENT columns")
// ErrNoAutoIncrementCols is returned when table has no AUTO_INCREMENT columns.
ErrNoAutoIncrementCols = errors.NewKind("table %s has no AUTO_INCREMENT columns")
)
// AutoIncrement implements AUTO_INCREMENT
type AutoIncrement struct {
UnaryExpression
autoIncVal *Literal
autoTbl sql.AutoIncrementTable
autoCol *sql.Column
}
// NewAutoIncrement creates a new AutoIncrement expression.
func NewAutoIncrement(ctx *sql.Context, table sql.Table, given sql.Expression) (*AutoIncrement, error) {
autoTbl, ok := table.(sql.AutoIncrementTable)
if !ok {
return nil, ErrAutoIncrementUnsupported.New(table.Name())
}
last, err := autoTbl.GetAutoIncrementValue(ctx)
if err != nil {
return nil, err
}
var autoCol *sql.Column
for _, c := range autoTbl.Schema() {
if c.AutoIncrement {
autoCol = c
break
}
}
if autoCol == nil {
return nil, ErrNoAutoIncrementCols.New(table.Name())
}
return &AutoIncrement{
UnaryExpression{Child: given},
&Literal{last, autoCol.Type},
autoTbl,
autoCol,
}, nil
}
// IsNullable implements the Expression interface.
func (i *AutoIncrement) IsNullable() bool {
return false
}
// Type implements the Expression interface.
func (i *AutoIncrement) Type() sql.Type {
return i.autoCol.Type
}
// Eval implements the Expression interface.
func (i *AutoIncrement) Eval(ctx *sql.Context, row sql.Row) (interface{}, error) {
// get value provided by INSERT
given, err := i.Child.Eval(ctx, row)
if err != nil {
return nil, err
}
// todo: |given| is int8 while |i.Right.Zero()| is int64
cmp, err := i.Type().Compare(given, i.Type().Zero())
if err != nil {
return nil, err
}
if given != nil && cmp != 0 {
// check if the given value is greater than autoIncVal
cmp, err := i.Type().Compare(given, i.autoIncVal.value)
if err != nil {
return nil, err
}
if cmp <= 0 {
// if it's less, return it and don't increment
return given, nil
}
i.autoIncVal = NewLiteral(given, i.Type())
}
val, err := i.autoIncVal.Eval(ctx, row)
if err != nil {
return nil, err
}
nextVal, err := NewIncrement(i.autoIncVal).Eval(ctx, row)
if err != nil {
return nil, err
}
i.autoIncVal = NewLiteral(nextVal, i.Type())
return val, nil
}
func (i *AutoIncrement) String() string {
return fmt.Sprintf("AutoIncrement(%s)", i.Child.String())
}
// WithChildren implements the Expression interface.
func (i *AutoIncrement) WithChildren(ctx *sql.Context, children ...sql.Expression) (sql.Expression, error) {
if len(children) != 1 {
return nil, sql.ErrInvalidChildrenNumber.New(i, len(children), 1)
}
return &AutoIncrement{
UnaryExpression{Child: children[0]},
i.autoIncVal,
i.autoTbl,
i.autoCol,
}, nil
}
// Children implements the Expression interface.
func (i *AutoIncrement) Children() []sql.Expression {
return []sql.Expression{i.Child}
}